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Title: Online pretreatment verification of high-dose rate brachytherapy using an imaging panel
Authors: Fonseca, Gabriel P.
Podesta, Mark
Bellezzo, Murillo
Van den Bosch, Michiel R.
Lutgens, Ludy
Vanneste, Ben G. L.
Voncken, Robert
Van Limbergen, Evert J.
RENIERS, Brigitte 
Verhaegen, Frank
Issue Date: 2017
Source: PHYSICS IN MEDICINE AND BIOLOGY, 62(13), p. 5440-5461
Abstract: Brachytherapy is employed to treat a wide variety of cancers. However, an accurate treatment verification method is currently not available. This study describes a pre-treatment verification system that uses an imaging panel (IP) to verify important aspects of the treatment plan. A detailed modelling of the IP was only possible with an extensive calibration performed using a robotic arm. Irradiations were performed with a high dose rate (HDR) Ir-192 source within a water phantom. An empirical fit was applied to measure the distance between the source and the detector so 3D Cartesian coordinates of the dwell positions can be obtained using a single panel. The IP acquires 7.14 fps to verify the dwell times, dwell positions and air kerma strength (Sk). A gynecological applicator was used to create a treatment plan that was registered with a CT image of the water phantom used during the experiments for verification purposes. Errors (shifts, exchanged connections and wrong dwell times) were simulated to verify the proposed verification system. Cartesian source positions (panel measurement plane) have a standard deviation of about 0.02 cm. The measured distance between the source and the panel (z-coordinate) have a standard deviation up to 0.16 cm and maximum absolute error of approximate to 0.6 cm if the signal is close to sensitive limit of the panel. The average response of the panel is very linear with Sk. Therefore, Sk measurements can be performed with relatively small errors. The measured dwell times show a maximum error of 0.2 s which is consistent with the acquisition rate of the panel. All simulated errors were clearly identified by the proposed system. The use of IPs is not common in brachytherapy, however, it provides considerable advantages. It was demonstrated that the IP can accurately measure Sk, dwell times and dwell positions.
Notes: [Fonseca, Gabriel P.; Podesta, Mark; Bellezzo, Murillo; Van den Bosch, Michiel R.; Lutgens, Ludy; Vanneste, Ben G. L.; Voncken, Robert; Van Limbergen, Evert J.; Verhaegen, Frank] Maastricht Univ, Med Ctr, GROW Sch Oncol & Dev Biol, Dept Radiat Oncol,MAASTRO, Dr Tanslaan 12, NL-6229 ET Maastricht, Netherlands. [Reniers, Brigitte] Hasselt Univ, CMK, Res Grp NuTeC, Agoralaan Gebouw H, B-3590 Diepenbeek, Belgium.
Keywords: brachytherapy; pretreatment verification; EPID;brachytherapy; pretreatment verification; EPID
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ISSN: 0031-9155
e-ISSN: 1361-6560
DOI: 10.1088/1361-6560/aa7028
ISI #: 000403564100001
Rights: © 2017 Institute of Physics and Engineering in Medicine
Category: A1
Type: Journal Contribution
Validations: ecoom 2018
Appears in Collections:Research publications

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